Percussion rhythm device for keyboard musical instruments



Aug. 11,1970

Filed May 18, 1966 A. B. WELSH I 3,524,009

PERCUSSION RHYTHM DEVICE FOR KEYBOARD MUSICAL INSTRUMENTS 3 Sheets-Sheet l o 0 u n S V i A%// I I" INVENTOR.

HLBN B. WELSH Aug. 11,1970 A. B. WELSH 3,524,009

PERCUSSION RHYTHM DEVICE FOR KEYBOARD MUSICAL INSTRUMENTS Filed May 18, 1966 3 Sheets-Sheet 2 452C Ova ImQmU WW R. Nm O H B .2 WWW E ow M m awn mwmw om 3mm; 5 v mm w Nu mm L wm H E; Q Y Q m m+ B aww Y on). vm 2 .523 9v W N Q mam HE 36 Qmm mv mozmk. mm vm wm mm a QE H mm Q v m+ mtq Nm 6N0 Wm mam QT vm mm 3 @Nm w s Y Q .csuSu MW mmmm mu5 7 8mm Q? mm Wm m (Om ww w f Aug. 1 1, 1970 A. B. WELSH PERCUSSION RHYTHM DEVICE FOR KEYBOARD MUSICAL INSTRUMENTS Filed May 18, 1966 3 Sheets-Sheet. 5

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. /owv--- 06 I547 ALAN B- WELSH I 34 BY US. Cl. 84-126 United States Patent 3,524,009 PERCUSSION RHYTHM DEVICE FOR KEYBOARD MUSICAL INSTRUMENTS Alan B. Welsh, Jasper, Ind., assignor to Kimball Piano & Organ Co., Jasper, Ind. Filed May 18, 1966, Ser. No. 551,024 Int. Cl. Gd 13/00; G10h 1/02 14 Claims ABSTRACT OF THE DISCLOSURE A selectable percussion rhythm sound effects arrangement for use with a keyboard musical instrument including bass, tenor, and treble keyboard sections, pedal section, a knee lever, and hand switch section. Each bass, tenor, and treble section is connectable from a voltage source by three or more switches and resistors through a differentiator, a trigger, a group of three or more transistor gates (interconnected with other groups of gates) controlled by selector switches to plural voice circuits and a crash cymbal circuit (the latter and one voice circuit being also connected to a white noise source), and thence selectably connected to plural amplifiers and speakers. Modifications provide for a foot switch, effective alone or with the keyboard. Diodes and plural switch terminals permit interconnection between the bass, tenor, and treble section.

This invention relates to a novel device for incorporatron 1n, or use with, a key operated musical instrument to provide accompaniment sounds therefor.

The total effect obtained by playing musical instruments is enhanced by accompanying the instrument by rhythm or percussion effects in the form of drums, castanets, wood blocks, cymbals, and the like. The types of musical instruments referred to are of the melodic type such as pianos, and organs, the like in which the several notes on the musical scale can be developed singly and in combination. The

'rhythm effect by the percussion devices referred to are those effects which are actually independent of any definite tonal characteristics and which would include the sounds produced by drums of various types, wood blocks,

, produced by the melodic instrument or instruments without' regard to the particular notes being played or the progression thereof. A distinction is thus made between melodic or tonal sounds having a predominating frequency which determines the pitch of the sound, and

rhythm or percussion sounds for accompaniment which are substantially atonal and which are made up of a mix- L ture of a large number of frequencies with no specific frequencypredominating. The atonal sounds referred to can,

in fact, be properly called noises, and a sound containing substantially all audible frequencies with none thereof predominating is often referred to as white noise.

With the foregoing in mind, a primary objective of the present invention is to provide a relatively simple inexpensive arrangement for generating sounds characteristic I} of percussion devices which produce substantially atonal sounds.

Another object of this invention is the provision of a device for developing the sounds of percussion devices and which device is adapted for incorporation with a key ice operated musical instrument in such a manner as to be actuated by the instrument.

A still further object of this invention is the provision of the combination of a key operated musical instrument and a device for producing percussion sound effects for accompaniment of the instrument in which the particular accompaniment effects can be selected at the will of the player of the musical instrument.

Still another object of this invention is the provision of a device for producing atonal percussion rhythm effects for accompanying a key operated melodic musical instrument in which the device can be readily incorporated in existing musical instruments or in new manufacture without any substantial change in the construction of the instrument.

The foregoing objects and advantages of the present invention, as well as still other objects and advantages thereof, will become more apparent upon reference to the following detailed specification taken in connection with the accompanying drawings in which:

FIG. 1 is a schematic perspective view showing a piano in which is incorporated a rhythm device according to the present invention;

FIG. 2 is a fragmentary sectional view indicated by line IIII of FIG. 1 showing how switches are incorporated in the instrument so as to be actuated by the keys when the keys are actuated;

FIG. 3 is a schematic plan view showing how the key operated switches of FIG. 2 are grouped to form one group in the lower register of the keys, a second group in the middle register of the keys, and a third group in the higher register of the keys;

FIG. 4 is a block diagram showing a complete circuit according to the present invention by means of which rhythm effects are developed simultaneously with the playing of the instrument;

FIG. 5 is a fragmentary view showing one form which one of the gates of the circuit of FIG. 4 can take;

FIG. 6 is a schematic showing of a modified circuit arrangement incorporating a foot switch by means of which the rhythm effect can be obtained by actuation of the foot switch on the downbeat and upbeat; and

FIG. 7 is a schematic showing of another circuit arrangement incorporating the foot switch and furthermore, incorporating additional circuitry by means of which the trigger for the treble section can be actuated not only by the treble keys but by keys in other sections of the keyboard as well.

Referring to the drawings somewhat more in detail, in FIG. 1 a piano 10 is illustrated which may be of substantially conventional construction. The piano embodies the keyboard 12 which consists of bass, tenor, and treble sections, as shownby the legends thereon. FIG. 1 is intended to show, generally, a key operated musical instrument and it will be understood that the instrument could be a piano of any type or an organ or any other key operated musical instrument that it might be desired to combine with the rhythm device according to the present invention.

FIG. 2 shows how a key 14 of the instrument can carry an abutment screw 16 for operating a switch 18. The switch, as will be seen, is normally held open by key 14 but, when key 14 is depressed during the playing of the instrument, switch 18 will be permitted to close. By permitting the switch to close under its own bias, contact bounce is eliminated. There is a switch 18 associated with each of the keys 14 of the instrument. The switches 18 are preferably combined in some sort of frame means 20 so that they can be installed as units in the musical instrument. The installation of the switch units in the instrument normally requires little, if any, change in the instrument structure. I

As will be seen in 'FI G. 3, the switches 18 are arranged in three groups with a-first group 22 pertaining to the bass section of the keys, a second group 24 pertaining to the tenor section of the keys and a third group 26 pertaining'to the treble section of the keys. Each key has a pertaining switch, and all of those in each of the 'bass, tenor and treble sections are connected in parallel.

The specific circuit arrangement by means of which the key switches control the generation of the percussion sounds is shown in FIG. 4.

It is well known in the electronic organ art to provide tone generators, generally in the form of precisely tuned oscillators, each of which continuously produces a specific frequency and which specific frequency pertaining to each oscillator is then divided to form octaves of the said frequency whereby a certain range of frequencies an octave apart are provided by each oscillator. Each oscillator in an electronic organ is tuned to correspond to one of the half steps of the musical scale and, thus, with a group of'12 oscilaltors arranged at intervals of one half step, and with each oscilaltor supplying a group of frequencies an octave removed from each other, a complete supply of frequencies necessary for the entire keyboard of the organ can be provided.

It is known in electronic organs to pass the generated frequencies through what are referred to as voice circuits and within which circuits the characteristic of the wave form of the current supplied thereto is so modified, by the superposition thereon of harmonics and overtones, that particular desired sound effects are obtained. For example, a voice circuit may modify the form of the wave supplied thereto by the oscillator so that the sound produced simulates a string instrument such as a violin or a cello, or a wood wind such as a clarinet, or simulates still other types of instruments. The usual organ contains a great may voice circuits with switches being provided in the form of tabs to select which of the voice circuits are to be active for modifing the wave form of the current supplied thereto.

With the present invention the same general scheme is employed but, inasmuch as the rhythm effects to be developed are substantially atonal, that is, made up of a mixture of a great many frequencies with no specific frequency predominating, it is not necessary to provide a plurality of tone generators. In addition, a characteristic of percussion rhythm effects is that they are generally quite brief in duration. For example, the individual sounds of wood blocks and castanets and drums are quite short and the sound of a cymbal crash is relatively short. Thus, for the production of sounds of this nature, which occur only short bursts, it is not essential to have a continuously running tuned oscillator or tone generator. Instead, an impulse developed by the closing of a key switch can often serve as the driver for driving a voice circuit in the form of a damped oscillator to cause the circuit to develop an output that can be amplified and then converted by a speaker into a percussion sound of the proper nature. In other cases, a simple generator can be supplied for driving a voice circuit with a signal consisting of mixed frequencies and this supply will be modified by the respective voice circuit to produce the particular sound desired when the voice circuit is triggered by an impulse from a key switch. The United States patent to Hearne 3,358,069 shows such a damped oscillator which is triggered by closing a switch 56 which will supply a pulse to point 46.

Referring now to FIG. 4, the switches 18 are shown in groups at the left. Only three switches for each of the bass, tenor and treble sections are shown but it will be understood that there would be as many switches in each section as there are keys in the pertaining section. Each switch 18 is connected to a voltage supply represented by wire 30 through a pertaining resistor 32 to one end of a summing resistor 34, the other end of which is grounded at 36. The end of resistor 34 adjacent resistor 32 is connected through a condenser 38 to one end of a resistor 40, the other end of which is grounded. The ungrounded end of resistor 40 is connected to the'input side of a trigger circuit 42.

Trigger circuit 42 is similar to a Schmitt trigger and, when triggered by an impulse caused by closing of a key switch,.is operablevto develop control impulse means. The trigger as shown develops one control impulse means at wire 44 and another at wire46. One of these control impulse means may be in the form of a substantially square pulse and the other may be substantially in the form of a needle or spike pulse. The production of such pulses is well known in the art and no specific circuitry for developing the pulses is illustrated.

The combination of resistors 32 and 34 forms a summing network so that even if some of'the switches 18 of a section of the switches are closed, the closing of a further switch in the section will increase the current supply to resistor 34 so that there will be a voltage rise thereacross which will be reflected through the differentiator made up of condenser 38 and resistor 40 to the input terminal of trigger circuit 42 so that the trigger circuit will develop'a pulse. Thus, trigger circuit 42 is'actuated upon the closing of any switch of the group of switches pertaining thereto at any time whether or not some of the switches pertaining thereto are already closed.

Each of the three groups of switches are connected in the same manner to their respective trigger circuits which are indicated at 48 and 50 respectively.

Moving now to the right side of the diagram of FIG. 4, a speaker is shown at 52 and is supplied by an amplifier 54 which, in turn, is supplied by a preamplifier 56. Preamplifier 56 has an input terminal connected to the output terminals of voice circuits which are indicated 58, 60, 62, and 64. Each of the voice circuits of the nature referred to above is adapted for either modifying a pulse of the respective trigger circuit, or a pulse of the respective trigger circuit in combination with another source of mixed frequencies for supplying a wave form to the preamplifier which will cause the resultant sound from the speaker to have the characteristics of a selected percussion device. In the circuit there is also shown an auxiliary frequency source 66 which may be in the form of a white noise generator, namely, a generator which will supply a mixture of substantially all frequencies. This generator is connected to voice circuit 58 and to voice circuit 64 to supply a driving input in the form of a mixed frequency thereto. Voice circuits 60 and 62 are not connected to generator 66 and derive their sole driving input from the impulses of the respective trigger circuits connected thereto.

Each voice circuit is connected to each of the trigger circuits 42, 48, and 50 via a normally closed gate. Thus, voice circuit 58 is connected via gate 58a with trigger circuit 42 and via gate 58b with trigger icrcuit 48 and via gate 580 with trigger circuit 50.

The voice circuit 60 is similarly connected by gates 60a, 60b, 600, with the same trigger circuits. Voice circuit 62 is connected by gates 62a, 62b, and 62c with'the trigger circuits 42, 48, and 50 in the same manner.

It is to be noted that the voice circuit 58 is driven by generator 66 and that the activating pulse supplied thereto from the respective trigger circuits is from a different terminal than the activating pulse that is supplied to voice circuits 60 and 62. This has already been commented on and it will be understood that one of the activating pulses from each trigger circuit could be, for example, a square wave pulse while the other could be in the form of a needle or spike pulse.

Still another voice circuit 64 is provided which is advantageously fed from generator means 66. This additional voice circuit may be for the purpose of supplying a crash cymbal sound and to this end is provided with its own separate switch 68 which may be under the control of a knee lever 70. The use of the crash cymbal sound is such that it is preferably brought in selectively and at infrequent intervals and would not to any advantage be under the control of the keys of the musical instrument. Each of the gates referred to is normally closed, i.e. nonconductive so that no signals will pass therethrough. Each gate, however, has a control terminal which upon the supply of a predetermined voltage thereto, will open, i.e. make conductive the respective gate and permit the gate to pass signals. The three gates 58a, 60a, and 62a thus have control terminals connected to a bank of three selector switches, indicated at 72. One selector switch is provided for each of the gates and can be adjusted either to open or close its respective gate. Thus, the three gates 58a, 60a, and 62a can all be closed or can all be opened or any one or more thereof can be opened.

Gates 58b, 60b, and 62b, are likewise provided with controlling selector switches 74 and gates 58c, 60c, and 62c are similarly provided with controlling selector switches 76.

As will be seen in FIG. 1 the selector switches 72, 74, and 76, are combined in a unit indicated at 78 which is positioned so as to be convenient to the player of the instrument whereby the selector switches can be adjusted whenever desired in order to bring in the desired rhythm efiects for the portion of the composition desired. The exact arrangement of the unit 78 is, of course, subject to change and it may be disposed along the front edge of the keys or be placed in a location beneath the keyboard, as shown, or may take the form of a row of tabs at the end of or above or in front of the keyboard, according to individual preference.

It is to be understood that as many voice circuits could be provided as might be desired. Included in the voice circuits contemplated are such as would simulate the bass drum, the snare drum, the brushes on a snare drum, castanets, wood blocks, and cymbals. With the exception of the crash cymbal sound, each voice circuit would have a gate pertaining to each section of the keys which were to activate the circuit. Some voice circuits might be connected to only one or two sections of the keys if so desired.

It is also contemplated to provide more than one speaker and to reproduce some of the sound effects from one speaker and other from another speaker thereby creating a spatial effect with the accompaniment sounds.

As to the nature of the gates referred to, one thereof, for example, gate 58a is shown schematically in FIG. 5. In this figure the incoming signal supplied by wire 46 passes through a differentiator 80 to the base of a transistor T1. The emitter of the transistor is connected to one end of grounded resistor 82 and is also connected by wire 84 to the input of the pertaining voice circuit. The collector of the transistor is adapted, through its pertaining selector switch 72a, to be connected to a source of bias voltage by wire 86 whereby closing of switch 72a will prepare transistor T1 to conduct whereas, when selector switch 72a is open, transistor T1 will not conduct. Other types of gates, of course, could be utilized and it will be understood that the showing in FIG. 5 is merely exemplary of one manner in which a gate could be provided for the circuit of FIG. 4 for connecting each voice circuit with the respective trigger circuits of the system.

The present invention lends itself to the creation of spatial etfects by providing additional speakers 52a and 52b with pertaining amplifiers, and switch means 520 and 52d by means of which the outputs from certain ones of the voice circuits can be directed to respective ones of speakers 52, 52a and 52b.

FIGS. 6 and 7 show circuit modifications in which a foot operated pedal is employed so that, for example, the rhythm effect selected for the base section of the keyboard is keyed upon pressing the foot pedal down on the downbeat, whereas the tenor section rhythm effect selected is keyed when the foot pedal is released on the upbeat. Still further, particularly in FIG. 7, there is shown an arrangement wherein a coupler is employed which enables the bass or tenor key switches, or both thereof, to serve as input for the treble trigger.

In both FIGS. 6 and 7 the same reference numerals are applied as in FIG. 4 where these reference numerals are applicable.

Referring first to FIG. 6, numeral represent a foot operated pedal which is provided with switch blades 102 and 104. Switch blade 102 is connected to the plus 6 volts line 30 and is normally open and, when foot pedal 100 is depressed, closes on its contact 106. Contact 106 is connected through resistor 108 with terminal 110 of a three position selector switch having moveable blade 112. Blade 112 is connected with the input side of condenser 38 forming a part of the dilferentiator connected to the input terminal of bass trigger 42 previously described.

When blade 112 is adjusted to a position of engagement with terminal 114, the bass keys supply input pulses to trigger 42 in the manner already described in connection with FIG. 4. When blade 112 is adjusted into contact with terminal 110, input pulses are supplied to trigger 42 only upon closing of switch blade 102 which, as mentioned before, is accomplished by the depressing of foot pedal 100, preferably the downbeat. When the adjustable blade 112 is adjusted into a center position in engagement with terminal 116, input pulses are supplied to trigger 42 from both foot pedal operated switch blade 102 and the key switches of the bass section of the keyboard. This is accomplished by the diodes D1 and D2, poled as indicated, so that impulses will pass through each thereof from its pertaining source to terminal 116 while the said sources are isolated from each other. The summing resistor, or bus, 34 is, of course, connected in the system just ahead of the ditferentiator condenser 38, as shown.

Associated with the trigger 48 of the tenor section of the keyboard is a further adjustable switch blade 118 having a first position of engagement with a terminal 120 which leads to the key switches of the tenor section of the keyboard. When the switch blade 118 is resting on contact 120 the operation of the rhythm effect device for the tenor section of the keyboard is exactly the same as that described in connection with FIG. 4.

Upon movement of blade 118 into engagement with terminal 122, however, the only input to trigger 84 is derived from wire 124 leading through resistor 126 to a terminal 128 pertaining to switch blade 104. Switch blade 104 is normally closed on terminal 128 and is separated therefrom upon depressing of foot pedal 100 and is returned to engagement with terminal 128 upon the releasing of foot pedal 100, the said releasing of the foot pedal 100, as mentioned, occurring on the upbeat.

Blade 104 can be connected directly to wire 30 but, in order to prevent a false signal to trigger 48 upon adjustment of switch blade 118 into engagement with terminal 112, it is preferred for blade 104 to be connected to a wire 130 leading from the output side of a diode D3 to one terminal of a condenser 132, the other side of which is grounded at 134. The input side of diode D3 is connected with terminal 106 pertaining to switch blade 102. It will be apparent that, upon depressing of foot pedal 100 to close switch blade 102 on its terminal 106, condenser 132 will receive a charge from wire 30. Thereafter, upon releasing foot pedal 100 so that switch blade 104 closes on its terminal 128, condenser 132 will discharge through switch blade 104 and resistor 126 and wire 124 and thereby supply an input pulse to trigger 48. This will occur when switch blade 118 is adjusted into contact with terminal 122. When switch blade 118 is not resting on terminal 122, condenser 132 will discharge through the relatively large resistor 136 to ground. The summing means, in the form of resistor 34 is, as before, connected to the circuit just ahead of the differentiator consisting of condenser 38 and resistor 40.

Switch blade 118 is also adjustable into engagement with a third terminal 138 and which terminal is adapted for receiving input impulses either from wire 124 or from 7 the treble key switches via the diodes D4 and D5 which are poled to pass impulses from their respective sources to terminal 138 while isolating the said sources from each other.

The key switches pertaining to the treble section of the keyboard in FIG. 6 are connected with the respective trigger 50 in the same manner as has already been described in connection with FIG. 4 so that no description thereof is given at this point.

Turning now to FIG. 7 there is shown a modification wherein the trigger pertaining to the treble section of the keyboard is adapted for being placed under the control solely of the switches pertaining to the treble section, or under the control of the said treble key swtiches together with the tenor key switches, or under the contol of all of the key switches of the keyboard.

In FIG. 7 the same foot pedal arrangement and switch blades operated thereby are employed as are shown in FIG. 6 and the same reference numerals are applied thereto. In FIG. 7, however, instead of the three position switch blades 112 and 118 there are employed, for the bass section, the two position switch blade 140, and for the tenor section, the two position switch blade 142.

When switch blade 140 is resting on its terminal 144 the bass key switches transmit impulses to the bass trigger 42 in the same manner as already described in FIG. 4.

When switch blade 140 is resting on its terminal 146, however, the input pulses to trigger 42 are derived solely from the foot pedal operated switch blade 102 as has already been described in connection with FIG. 6.

Similarly, in the tenor section, when switch blade 142 is resting on terminal 148, the input pulses to tenor trigger 48 are derived solely from the tenor key switches. When switch blade 142 is resting on terminal 150, the only input pulses to tenor trigger 48 are derived from foot pedal operated switch blade 128 in a manner already described in connection with FIG. 6.

The treble trigger 50 is connected, as shown in FIG. 7 to a three position switch blade 152 which, when it is resting on its terminal 154, connects the key switches of the treble section with trigger 50 so as to supply input pulses thereto, in the same manner as has already been described in connection with FIG. 4.

When blade 152 is adjusted into engagement with its terminal 156, the key switches of the treble section supply input pulses to treble trigger 50 via diode D6, terminal 156 and blade 152. At the same time the closing of the key switches of the tenor section will also supply impulses to terminal 156 via diode D7. Diodes D6 and D7 isolate the key switches of the tenor and treble section from each other.

Whenever switch blade 142 is closed on its terminal 148, no signals will be transmitted from the tenor keys via diode D7 to terminal 156 because the voltage across the diode at that time will be insufiicient to cause the diode to conduct.

When switch blade 152 is closed on its terminal 158, the key switches of the treble section will supply impulses to terminal 158 via diode D8 while the tenor key switches will supply impulses thereto via diode D9 while,

furthermore, the bass key switches will supply impulses to terminal 158 via diode D10. Diodes D8, D9, and D10, of course, eifectively isolate the groups of key switches from each other.

Diode D9 is similar to diode D7 and will not supply input pulses to terminal 158 when switch 142 is closed on its terminal 148. Similarly, diode D10 will not supply impulses to terminal 158 when switch 140 is closed on its terminal 144.

The arrangement of FIG. 7 provides that, when the switches 140 and 142 are adjusted to place the bass and tenor triggers 42 and 48 under the control of the foot pedal operated switch blades, the treble trigger 50 can be placed under the control of (a) the treble key switch only, (b) the treble and tenor key switches together, or (c) of all the key switches of the keyboard.

With all three keying sections in FIG. 7, the summing means, or bus, is connected just ahead of the pertaining ditferentiator, thereby to provide a path for the discharge of the difierentiator condenser.

It will be understood that this invention is susceptible of modification within the scope of the appended claims.

What is claimed is:

1. In a device adapted for incorporation in a keyboard type musical instrument for producing percussion rhythm sound elfects independent of the sounds produced by the instrument to accompany the instrument; generating means for generating electrical signals at frequencies conforming to the frequencies of the desired percussion sounds, amplifier and speaker means connected to the generating means to receive said signals therefrom and operable to convert the signals into sound, said generating means having input terminal means and being responsive to the supply of pulses to said input terminal means to supply said signals to said amplifier and speaker means, a key switch pertaining to each of at least some of the keys of the instrument and actuated by the pertaining key when the key is actuated, a source of voltage connected to one side of said key switches, said key switches being connected in parallel in at least two groups pertaining respectively to different regions of a single keyboard of the instrument, a plurality of normally nonconductive gate means having input terminals adapted to receive pulses and output terminals connected to selected ones of the said input terminal means of said generating means to supply the pulses thereto, each gate means having a voltage sensitive control terminal, selector switch means connected between a source of control voltage and the control terminals of said gate means and adjustable for selectively making single ones or groups of said gate means conductive 0r nonconductive, respective pulse developing means connected between the other sides of said groups of said key switches and the input terminals of respective ones of said gate means, each said pulse developing means including summing means on the input side thereof, each pulse developing means being responsive to the actuation of any of the key switches of the respective group by actuation of the pertaining instrument key for supplying an actuating pulse to the input terminals of the said gate means connected thereto.

2. A device according to claim 1 in which each said pulse developing means includes a trigger circuit connected between the said respective summing means and the input terminals of the respective gate means.

3. A device according to claim 2 in which said generating means comprises a plurality of voice circuits, each operable for developing mixed frequencies conforming to a particular percussion device sound, said terminal means comprising an input terminal for each voice circuit, and said gate means comprising gates interposed between said input terminals of said voice circuits and the output sides of the respective trigger circuits.

4. A device according to claim 3 in which the said single keyboard of the instrument is divided into upper, lower, and middle ranges and a respective group of key switches is provided for each said range.

5. In combination; a keyboard musical instrument having sound producing means under the control of the keys thereof, a key switch pertaining to each key of the instrument and actuated in response to actuation of the pertaining key, said switches being connected in parallel in groups, one of said groups pertaining to each of the lower, middle, and upper ranges of the keyboard of said instrument, generating means for generating mixed frequencies conforming substantially to the frequency characteristics of the sounds produced by substantially atonal percussion devices, amplifier and speaker means connected to the output sides of said generator means to receive the generated frequencies therefrom and convert the frequencies into sound independently of the sounds produced by the said sound producing means, said generator means including a plurality of voice circuits each pertaining to a predetermined percussion device sound, each voice circuit having an input terminal responsive to a control pulse to cause the pertaining voice circuit to supply the frequencies peculiar thereto to said amplifier and speaker means, a trigger circuit for each group of key switches, each trigger circuit having their input side thereof operatively connected to the respective group of key switches and operable upon the closing of a switch of the pertaining group to generate control pulse means, normally closed gates connected between the output sides of said trigger circuits and said input terminals of said voice circuits, and selector switch means connected to said gates in controlling relation thereto operable for selectively opening and closing said gates singly or in multiple.

6. The combination according to claim in which a summing network is connected between the input side of each said trigger circuit and the pertaining group of key switches.

7. A device according to claim 6 in which a further voice circuit means is provided for producing frequencies characteristic of a cymbal sound, said further voice circuit means having its output side connected to said amplifier and speaker means, and a separate player operated switch connected to the input side of said further voice circuit means for the selective actuation thereof.

8. In a device for developing percussion rhythm sound efiects simulating the sound of percussion devices and adapted for use with a keyboard type musical instrument; a plurality of generators each operable for developing a frequency mixture which simulates the sound of a respective percussion device when the frequency mixture is amplified and supplied to a speaker, each said generator having an output terminal adapted for connection to sound producing means and also having an input terminal responsive to input pulses to actuate said generator to cause the generator to supply said signals to the said output terminal thereof, at least some of said generators comprising means for supplying said signals to said output terminal thereof for a predetermined time following the supply of an input pulse to the said input terminal thereof, a plurality of normally closed gates, said gates having output terminals connected to the input terminals of said generators and each also having an input terminal and a control terminal, control switches connected to said control terminals and operable for selectively opening and closing said gates singly and in multiple, trigger circuit means having outputs connected to the input terminals of said gates, input pulse developing means connected to the input sides of said trigger circuit means, a source of voltage, summing means connected to the input sides of said trigger circuit means, switch means connected on one side to said source of voltage, said switch means including a foot operated switch and a plurality of other switches, each said other switch being adapted for operation by a respective key of a musical instrument, selector switch means having first terminal means connected to the other side of said foot operated switch to receive voltage therefrom upon actuation of the foot operated switch, and second terminal means connected to the other side of at least some of said other switch means to receive voltage therefrom upon actuation thereof, said selector switch means having moveable blade means connected to the input sides of said summing means and adapted for being selectively adjusted into a first position of engagement with said first terminal means and a second position of engagement with said second terminal means.

9. A device according to claim 8 in which said selector switch has third terminal means selectively engageable by said switch blade means and a diode connected between each of said first and second terminal means and the respective third terminal means and poled in the same direction with respect to said third terminal means.

10. A device according to claim 9 in which said gates are arranged in three groups and said trigger circuit means comprises a trigger circuit for each of the three groups of gates, said pulse developing means comprising a pulse developing means for each of the three trigger circuits, summing means included in each of said three pulse developing means on the input side thereof, and said other switches comprising first, second and third groups of switches with each group thereof connected to a respective one of the three summing means.

11. A device according to claim 10 in which said foot operated switch comprises first and second foot operated switch blades, each said foot operated switch having an output terminal, said first blade closing on its output terminal upon actuation of the foot operated switch and said second blade closing on its output terminal upon release of said foot operated switch, a voltage appearing at each output terminal when its blade closes thereon, said selector switch means comprising a pair of selector switches each having a blade connected to the input side of the pulse developing means pertaining to a respective one of said first and second groups of switches, each said selector switch means having the said first terminal thereof connected to the output terminal of a respective one of said first and second foot operated switch blades.

12. A device according to claim 11 in which a capacitor is provided connected to the output terminal of said first foot operated switch blade so as to receive a charge therefrom when said first foot operated switch blade is closed, said capacitor being connected to said second foot operated switch blade to supply voltage therethrough to the output terminal thereof when said second foot operated switch blade closes when said foot operated switch is released following actuation thereof.

13. A device according to claim 11 in which a still further selector switch is provided having a blade connected to the input side of the one of said summing means pertaining to said third group of switches, first, second and third terminals selectively engageable by the blade of said further selector switch, said first terminal being connected to said third group of switches, first and second diodes connecting said second terminal to said second and third group of switches respectively, and third, fourth and fifth diodes connecting said third terminal to said first, second and third groups of switches respectively, all of said diodes being poled in the same direction in respect of the said terminals to which they are connected.

14. A device according to claim 13 in which each of said first, third and fourth diodes has a threshold voltage of such that it will permit voltage to pass therethrou-gh to the respective terminal of said further selector switch only when the respective said selector switch blade connected to said first and second pulse developing means is in its said first position.

References Cited UNITED STATES PATENTS 3,309,454 3/1967 Cutler 841.13 X 3,003,383 10/1961 Williams 841.26 2,783,672 3/1957 Hanert 841.26 3,358,069 12/1967 Hearne 84-1.03 2,889,467 6/1959 Endres et a1. 307-253 3,417,189 12/1968 Kramer 841.19 3,433,880 3/1969 Southard 84-1.17 3,439,569 4/1969 Dodds et a1 84-126 WARREN F. RAY, Primary Examiner 

